This is one of those worthless and time wasting repairs but it's bugging me and I want to figure it out. Simple 9v 1a SMPS wall wart and it's bouncing between 8.2 and 9.4v without load. I've pulled out every single cap and all tested fine. I've replaced the opto and same exact issue. All diodes are testing fine. I'm not sure if the IC can cause this or if the IC had issues you wouldn't get anything at all on output.
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9v super basic wall wart issue
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9v super basic wall wart issue
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Re: 9v super basic wall wart issue
I'll check later tonight--------------------------------------------------------------
Ryzen 3600x
16GB Patriot 3600MHz
MSI B450 Gaming Plus
MSI Air Boost Vega 56
Acer 32" 1440P Freesync
Rosewill Capstone 750W
--------------------------------------------------------------
Hakko FX-888D Station
FX-8802 Iron
MG Chem .8mm 63/37 RA 2.2%
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Re: 9v super basic wall wart issue
I pulled all caps one by one and they all checked out. I can replace it anyway but don't know what good it will do--------------------------------------------------------------
Ryzen 3600x
16GB Patriot 3600MHz
MSI B450 Gaming Plus
MSI Air Boost Vega 56
Acer 32" 1440P Freesync
Rosewill Capstone 750W
--------------------------------------------------------------
Hakko FX-888D Station
FX-8802 Iron
MG Chem .8mm 63/37 RA 2.2%
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Re: 9v super basic wall wart issue
Originally posted by kaboom View PostThe 431 may be hunting.
Try a 150-1k resistor across the IR LED in the opto.
Points are marked in attached image.
Change the small cap on pri side to 22u/50v or 47u/50v.
Ok, pulled the resistor off and it's still good. Pulled C3 which was a 10uf 50v cap and replaced with a Panasonic FC 47uf 50v.Last edited by jayjr1105; 03-03-2022, 09:45 PM.--------------------------------------------------------------
Ryzen 3600x
16GB Patriot 3600MHz
MSI B450 Gaming Plus
MSI Air Boost Vega 56
Acer 32" 1440P Freesync
Rosewill Capstone 750W
--------------------------------------------------------------
Hakko FX-888D Station
FX-8802 Iron
MG Chem .8mm 63/37 RA 2.2%
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Re: 9v super basic wall wart issue
Soldering heat from R&R'ing C3 may have temporarily "woken" it up.
The 431 seems to need a minimum load; when an unbypassed opto LED is the sole source of current to the 431, the latter can hunt.
Leading to voltage "bounce" at no load.
Perhaps it was C3.
With the original C3 in place, leave it out in the cold a while- it'll probably act up afterwards= cap(s) is/were suspect.
In similar SMPS wall warts, I've used 22-47u/50v caps, PW/HE/FC, for C3.
If a new C3 keeps it stable, even cold, you can probably leave the opto LED unbypassed."pokemon go... to hell!"
EOL it...
Originally posted by shango066All style and no substance.Originally posted by smashstuff30guilty,guilty,guilty,guilty!
guilty of being cheap-made!
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Re: 9v super basic wall wart issue
Originally posted by kaboom View PostSoldering heat from R&R'ing C3 may have temporarily "woken" it up.
The 431 seems to need a minimum load; when an unbypassed opto LED is the sole source of current to the 431, the latter can hunt.
Leading to voltage "bounce" at no load.
Perhaps it was C3.
With the original C3 in place, leave it out in the cold a while- it'll probably act up afterwards= cap(s) is/were suspect.
In similar SMPS wall warts, I've used 22-47u/50v caps, PW/HE/FC, for C3.
If a new C3 keeps it stable, even cold, you can probably leave the opto LED unbypassed.--------------------------------------------------------------
Ryzen 3600x
16GB Patriot 3600MHz
MSI B450 Gaming Plus
MSI Air Boost Vega 56
Acer 32" 1440P Freesync
Rosewill Capstone 750W
--------------------------------------------------------------
Hakko FX-888D Station
FX-8802 Iron
MG Chem .8mm 63/37 RA 2.2%
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Re: 9v super basic wall wart issue
BTW, got home and still tested very stable around 9.2v.--------------------------------------------------------------
Ryzen 3600x
16GB Patriot 3600MHz
MSI B450 Gaming Plus
MSI Air Boost Vega 56
Acer 32" 1440P Freesync
Rosewill Capstone 750W
--------------------------------------------------------------
Hakko FX-888D Station
FX-8802 Iron
MG Chem .8mm 63/37 RA 2.2%
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